Insulation of wires for telegraph-lines



(No Model.)

T. J. MAYALL. INSULATION OF WIRE FOR TELEGRAPH LINES.

Patented 00. 2, 1883.

UNITED STATES PATENT OFFICE.

THOMAS J. MAYALL,.OF READING, MASSACHUSETTS.

INSULATION OF WIRES FOR TELEGRAPH-LINES.

SPECIFICATION forming part of Letters Patent No. 286,035, dated October2, 1883, Application filed June 22, 1%81. (No model.)

To all whom,- it may concern.-

Be it known that I, THOMAS J. MAYALL, of Reading, in the county ofMiddlesex and Commonwealth of Massachusetts, have invented a.

new and useful Improvement in'the Insulation of fires forTelegraph-Lines, of which the following is a specification.

My invention relates to the compounds of materials used for insulatingwires and the manner of applying the insulating materials to the wires,the object of it being an improvement upon the method of insulatingwires set forth in my application for a patent filed March 24, 1881,whereby greater convenience of manipulation in the manufacture issecured and more satisfactory results are attained.

The invention set forth in my application for a patent above referred toconsisted in embedding the wire or wires to be insulated in the middleof an elongated mass in the form of a strap or belt or cord of acompound of rubber, graphite, and sulphur vulcanized on the wire orwires. In practice, I have found that there is some liability toimperfections caused by "ulcanizing the compound on the wires, which mypresent invention will obviate; and, also, that the product is moreconveniently handled and can be made in much greater lengths.

My present invention consists in first covering the wire to beIILSIIQQQCLWIIIII a coating of aplasti'compound of rubber and graphite,withTt'sTiIphur, and then putting on over this covering a layer ofrubber, graphite, and sulphur, vulcanized before applying it, andcompletely uniting it with the inner covering of rubber and graphite bycement and pressu re. Thus the wire is only in contact with the compoundof rubber and graphite, which is a perfect insulator, and has notendency to corrode the wire. The outer coating of rubber, graphite, andsulphur, vulcanized, pro tools the inner unvulcanized coating from theaction of the atmosphereand moisture, and also strengthens theinsulation and renders the insulated wire less liable to injury byviolence.

To practice my invention, I make a compound of rubber, one pound toabout one and one-half pounds of graphite mixed and thoroughly blendedtogether bygrinding or other It therefore requires protection.

suitable means. I run this compound into sheets of proper thicknessaboutone thirtysecond part of an inch. I then cut the sheets into strips ofthe desired width, and unite the strips end to end to attain the lengthrequired. A wire or a gang of several wires is laid between two of thesestrips in such manner that if there are more than one they do not toucheach other, and then the two strips of rubber and graphite arecompressed in any convenient way with sufficient force to completelyweld them into one homogeneous strip, with the insulated wires in themiddle of it. This compound being without sulphur cannot be and is notvulcanized, and is comparatively soft, and will not bear violent contactwith hard bodies, and has very little tensile strength. For this purposeI make a compound of rubber one pound,

which I thoroughly mix and blend together into a plastic mass bygrinding or other suitable means, and then run itinto sheets of properthickness, (about one-sixteenth of an inch,) out the sheet into stripsof suitable width,

join the strips together end to end, and then vuleanize. or cure thestrips by heat to a degree to leave them pliable and somewhat elastic. Ithen lay one of these strips on each side of the strip of rubber andgraphite compound containing the wire or wires, uniting them with it bycement and sufficient pressure to completely weld the three strips intoone. Thus I get the strength and durability of the vulcanized rubber andgraphite and sulphur compound, and at the same time perfectly insulatethe wire or wires and prevent them from coming in contact with thecompound containing sulphur.

In the drawings annexed, Figure 1 shows a gang of wires partiallyinclosed in coverings of rubber and graphite compound. Fig. 2 shows a(-rosssectiou of wires and rubber and graphite compound.

a are wires. 0 is the inner coating of rubber and graphite compoundunvulcanized. e is the outer coating of rubber and graphite compoundvulcanized.

I claim as new and my invention- 1. An electrical conductor coated witha graphite two and one-half to few; pounds, and sulphur about two tofour ounces;

compound of rubber and graphite not vulcanized, and enveloped outsidesaid coating with a compound of vulcanized rubber and graphitesubstantially as described.

5 2. A compound electrical conductor comprising a series of parallelwires embedded and separated from each other by an unvnleanized rubbercomposition, and an exterior envelope or covering of vulcanized rubberand x0 graphite, substantially as described.

3. An electrical conductor coated with an insulating composition ofrubber and graphite mwuleanized and free from sulphur, snbslnir tiallyas described.

4. As an electrical insulating inedinin. an 15 unvulcanized compound ofllll)l)(l'2lll(l graph ite, substantially as described.

THOS. J. MAYALL.

\Vitnesses:

Gus. HoUoI-I'rox H. KENNEY, Jr.

